本研究以A508為底材，覆銲層為Inconel 52M，藉由GTAW及PTAW兩種不同之銲接工法，由Half Weld-bead之銲接方式，在A508表面，覆銲不同層數及不同道次之Inconel 52M覆銲層，探討不同銲接工法及不同銲接參數，對於底材及覆銲層之顯微結構影響。並於3.5 wt.% 鹽水環境中進行動電位試驗，測驗A508底材及52M覆銲層不同區域之常溫抗蝕能力。
實驗結果顯示，GTAW及PTAW兩種銲接工法，於A508熱影響區中，熱影響範圍最深不會超過第一層覆銲層所造成之熱影響範圍，下一道次之入熱量，會使前一道次之熱影響區再次受熱，微觀組織晶粒細化。在覆銲層銲冠處產生富Cr之相，對於搭接下一道次有不良的影響。動電位試驗中，銲道之抗蝕能力優於熱影響區；單道次銲道及叁層覆銲後銲道相比，隨著覆銲層數增加，覆銲層中Ni與Cr的含量愈外層愈高。後續覆銲時，因為局部重融，可使前一層熔融區中的Ni與Cr成分上升，腐蝕電位也隨之上升，抗蝕能力增加。

In this study, cladding layer of Inconel 52M was deposited on A508 substrate material. Several layers and passes of Inconel 52M were welded on the surface of A508 by Half Weld-bead method using two welding processes namely GTAW and PTAW. Different welding methods and different welding parameters were found to have some effects on the microstructure of both the substrate material (A508) and the cladding layer (Inconel 52M). Dynamic potential test was carried out using 3.5 wt.% NaCl to check corrosion resistance on the cladding layer of Inconel 52M in comparison to the substrate material A508.
The experimental results for both welding methods of GTAW and PTAW shows that, the heat affected zone (HAZ) on the substrate material is maximum in depth during the first layer cladding. With the subsequent cladding layers, HAZ on the substrate material due to thermal impact become less and less as the number of layers increases. On the other hand, it was observed that the next pass affect the grain refinement of the previous pass. Chromium segregation at the surface boundary of each pass has negative impact on both the microstructure and strength of the entire cladding. Dynamic potential test shows better corrosion resistance on the weld bead layer of Inconel 52M compared to the heat affected zone and the substrate material A508. Comparison of single layer to three layers, welding shows contents of Cr and Ni increases with the number of layers. Thus less in single layer but more in three layers due to rise of Ni and Cr in each layer deposits as the remelt takes place. Increased number of layers also shows increased corrosion resistance.

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